Racemic bupivacaine is an effective long-acting local anaesthetic, and may be given as an epidural. However, racemic bupivacaine is cardiotoxic, having depressant electrophysiological and mechanical effects on the heart. It should therefore be used with caution in cardiac-compromisedpatients, and the use of high doses and high concentrations is contraindicated.
In particular, bupivacaine has produced death in a number of patients, including women in childbirth and when used in the Bier's block technique. Although the incidence of death has been relatively small, the concern has been sufficient to stop the use of 0.75% bupivacaine for obstetrics and the prescribing of bupivacaine for use in Bier's blocks.
In addition, due to its mode of action, directly on the nervous system, at higher doses bupivacaine is known to have undesirable central nervous system (CNS) side-effects which, prima facie, are connected to its anaesthetic activity. Indeed, the occurrence of CNS side-effects is one of the major factors limiting the use of this drug in normal clinical practice employing techniques such as local infiltration, nerve block, field block, epidural and spinal blocks.
It is known that levobupivacaine is probably less cardiotoxic than dexbupivacaine and racemic bupivacaine. See, for example, Vanhoutte et al. (1991) Br. J. Pharmacol. 103:1275-1281, and Denson et al. (1992) Regional Anaesthesia 17:311-316. Vanhoutte et al. studied the effects of bupivacaine enantiomers on the electrophysiological properties of guinea pig isolated papillary muscle; this is based on their statement that "the cardiotoxicity of bupivacaine seems to be mainly of electrophysiological origin."